Philosophers commonly define knowledge as justified true beliefs. A heated debate exists, however, about what makes a belief justified. In this article, we examine the question of belief justification from a psychological perspective, focusing on the subjective confidence in a belief that the person has just formed. Participants decided whether to accept or reject a proposition depicting a social belief, and indicated their confidence in their choice. The task was repeated six times, and choice latency was measured. The results were (...) analyzed within a Self-Consistency Model of subjective confidence. According to SCM, the decision to accept or reject a proposition is based on the on-line sampling of representations from a pool of representations associated with the proposition. Respondents behave like intuitive statisticians who infer the central tendency of a population based on a small sample. Confidence depends on the consistency with which the belief was supported across the sampled representations, and reflects the likelihood that a new sample will yield the same decision. The results supported the assumption of a commonly shared population of representations associated with each proposition. Based on this assumption, analyses of within-person consistency and cross-person consensus provided support for the model. As expected, choices that deviated from the person’s own modal judgment or from the consensually held judgment took relatively longer to form and were associated with relatively lower confidence, presumably because they were based on non-representative samples. The results were discussed in relation to major epistemological theories – foundationalism, coherentism and reliabilism. (shrink)